The present invention relates generally to a water supply decontamination system, and is particularly concerned with a decontamination system for water lines used in dental offices and other medical facilities.
Water supplies in all health care facilities have the potential for contamination by disease causing bacteria and viruses. The municipal water supply is known to carry certain bacteria, but the bacteria are usually present in such low numbers that they present no hazard. However, when such water is supplied to a dental water line, and stands in the line for extended periods, a bacterial biofilm forms on the plastic tubing due to the very high surface area to volume ratio of the tubing. The biofilm acts as a breeding ground for such disease producing bacteria as Pseudonomas, Klebsiella and Legionella. In addition, contamination also occurs from "suck-back" of fluids from the patient's mouth into the dental handpiece. As a result, water supplied from a dental water line to rinse a patient's mouth is often grossly contaminated and would not meet the standards required for municipal drinking water.
A fine aerosol mist is created by dental handpieces and the like, so that bacteria present in the water line are dispersed into the air and will be inhaled by both patient and dental personnel. This allows bacteria to enter the respiratory tract and has been shown to lead to infection or disease in some cases.
Another problem arising from the build-up of a biofilm in dental or other medically used water lines is that the biofilm is liable to spread back from the contaminated water line and into the building water supply lines. This has been shown to have occurred in some buildings, and such contamination is extremely difficult to eliminate.
The American Dental Association recommends flushing dental water lines for two minutes or more at the start of each day and before each patient. However, this has not proved to be sufficient to remove the source of contamination, which is the biofilm formed as a coating on the water line. Thus, after flushing, testing has shown that the dental unit water line water still regularly fails to meet the U.S. public health requirements for potable water (i.e. 500 C.F.U. s/ml).
Another solution which has been tried is to supply water to the lines from a sterile source, rather than using the municipal water supply. However, contamination of the line and water reservoir can still occur as a result of suck-back or retraction of fluids from the patient's mouth. Bacterial growth will be amplified as a result of the water standing in the line, and growth of a biofilm will eventually occur.
Another method which has been proposed to deal with this problem is to provide a bacterial filter on the delivery side of the water supply line. Again, this does not deal with the problem of the biofilm formed on the water supply line, and will itself become a source of patient cross-contamination if not changed frequently, due to bacterial growth directly on the filter. Additionally, although it serves as a barrier to suck-back contamination, bacteria caught on the filter from a patient's mouth may be flushed into the next patient's mouth. This is no different than if it merely flowed into the water lines.
Another approach is to disinfect the dental water line using sterilizing agents. However, this does not always eliminate the biofilm, from which bacteria break off and provide a source of contamination to water subsequently flowing through the line, and is inconvenient and time consuming with existing systems. Also, cross-contamination between patients is still possible.
Up to now, no effective and convenient method or system for effectively decontaminating dental and other water lines has been proposed. However, such a system is clearly needed in view of the potential for both patients and medical personnel to contract diseases as a result of contamination of such water lines.